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Optimize unpack_vectors() by not shuffling around redundant vectors.

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Inspired by guidance from Dark Shikari. On a Core 2 Duo 2.0 GHz, this
change decodes the 10-minute Big Buck Bunny 1080p short about 2 seconds
faster.

Originally committed as revision 20895 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Mike Melanson 2009-12-19 07:33:10 +00:00
parent b2cc8111d6
commit e6e32bdc5f
1 changed files with 7 additions and 15 deletions
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22
libavcodec/vp3.c
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@ -891,11 +891,6 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb)
motion_y[0] = fixed_motion_vector_table[get_bits(gb, 6)];
}
for (k = 1; k < 6; k++) {
motion_x[k] = motion_x[0];
motion_y[k] = motion_y[0];
}
/* vector maintenance, only on MODE_INTER_PLUS_MV */
if (s->macroblock_coding[current_macroblock] ==
MODE_INTER_PLUS_MV) {
@ -946,10 +941,6 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb)
/* all 6 fragments use the last motion vector */
motion_x[0] = last_motion_x;
motion_y[0] = last_motion_y;
for (k = 1; k < 6; k++) {
motion_x[k] = motion_x[0];
motion_y[k] = motion_y[0];
}
/* no vector maintenance (last vector remains the
* last vector) */
@ -960,10 +951,6 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb)
* last motion vector */
motion_x[0] = prior_last_motion_x;
motion_y[0] = prior_last_motion_y;
for (k = 1; k < 6; k++) {
motion_x[k] = motion_x[0];
motion_y[k] = motion_y[0];
}
/* vector maintenance */
prior_last_motion_x = last_motion_x;
@ -974,8 +961,8 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb)
default:
/* covers intra, inter without MV, golden without MV */
memset(motion_x, 0, 6 * sizeof(int));
memset(motion_y, 0, 6 * sizeof(int));
motion_x[0] = 0;
motion_y[0] = 0;
/* no vector maintenance */
break;
@ -992,8 +979,13 @@ static int unpack_vectors(Vp3DecodeContext *s, GetBitContext *gb)
current_fragment, s->fragment_count);
return 1;
}
if (s->macroblock_coding[current_macroblock] == MODE_INTER_FOURMV) {
s->all_fragments[current_fragment].motion_x = motion_x[k];
s->all_fragments[current_fragment].motion_y = motion_y[k];
} else {
s->all_fragments[current_fragment].motion_x = motion_x[0];
s->all_fragments[current_fragment].motion_y = motion_y[0];
}
}
}
}